Is “Delete Vignetted” turned on in the footprint diagram settings?

There might be mismatch between the rays traced for the Footprint Diagram and those you are tracing in the merit function.

Your REAX operands have Px =1 and Py =1 and this actually specifies a rays that is outside of the system entrance pupil and so won’t be traced for the Footprint diagram. As per the Help Files Normalized Pupil Coordinates

If you changed your REAX operand to trace Px=1, Py=0 then you should get a better match, although this assumes that this marginal ray is at the edge of the footprint on your surface of interest.

Yes, it appears that the choice of the (Px,Py) values when computing REAX does indeed make a difference when comparing the result to the footprint diagram.  After conducting a simple test, it looks like a rotation (about z) is also required in order to see the seemingly inconsistent values (i.e., the surface at which the footprint diagram is evaluated has a local coordinate system that is rotated about z with respect to the stop surface).

Here is a simple test model that illustrates the behavior.  It is nothing more than a stop surface illuminated by an on-axis collimated beam, followed by another surface (in contact with the stop) that is used for evaluation of the footprint diagram and is optionally rotated about z.  There are two configurations.  Config 1 has no rotation, while Config 2 has a rotation of 45 degrees.  For Config 1 there is no apparent discrepancy, but for Config 2 there seemingly is (although this is not an error as the software is doing exactly as told).

Config 1

Config 2

Regards,

Jeff